I applied for U.S. Green Card for my husband, the Form I-130 has been approved. We were told that the I-485 application is in the process of background checks by FBI, after their fingerprinting. What is the background check process, and how long it may take? 

Answer:

All applicants for a U.S. immigration benefit are subject to criminal and national security background checks to ensure they are eligible for that benefit. U.S. Citizenship and Immigration Services (USCIS), the Federal agency that oversees immigration benefits, performs checks on every applicant, regardless of ethnicity, national origin or religion.

FBI name checks are also required for many applications. The FBI name check is totally different from the FBI fingerprint check. The records maintained in the FBI name check process consist of administrative, applicant, criminal, personnel and other files compiled by law enforcement. Initial responses to this check generally take about two weeks.

In about 80 percent of the cases, no match is found. Of the remaining 20 percent, most are resolved within six months. Less than one percent of cases subject to an FBI name check remain pending longer than six months. Some of these cases involve complex, highly sensitive information and cannot be resolved quickly.

Even after FBI has provided an initial response to USCIS concerning a match, the name check is not complete until full information is obtained and eligibility issues arising from it are resolved.

http://www.greencardfamily.com/question/question2014/I485-Background-Check_0317.htm